Analyzing power measurements in pion deuteron absorption at low energies.

Abstract

As part of an experimental study of the \ensuremath{\pi}NN system, the pion absorption reaction, ${\mathrm{\ensuremath{\pi}}}^{+}$d\ensuremath{\rightarrow}\ensuremath{\rightarrow}pp, is investigated at low energy. Angular distributions of the vector analyzing power, ${\mathit{iT}}_{11}$, are presented for six complementary angle pair coincidences at 65 MeV and five pairs at 25 MeV. There is good agreement with previous measurements, and a significant improvement in uncertainties has been achieved. Results are compared with theoretical predictions based on three different approaches. The best agreement is with a relativistic Faddeev calculation by the Lyon group. Calculations based on the partial wave solutions of Arndt et al. are compared with the data at both energies.